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Regional Differences in Breast Cancer Survival Despite Common Guidelines Sonja Eaker,1 Paul W. Dickman,2 Vivan Hellstro¨m,1 Matthew M. Zack,3 Johan Ahlgren,4,5 ¨ rebro Breast Cancer Group Lars Holmberg,1 and the Uppsala/O 1 Department of Surgery, University Hospital of Uppsala and the Regional Oncologic Centre, Uppsala, Sweden; 2Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; 3U.S. Department of Health and Human Services, Centers for Disease Prevention and Control, National Center for Chronic Disease Prevention and Control, Division of Adult and Community Health, Atlanta, Georgia; 4Department of Oncology, Ga¨vle Hospital, Ga¨vle, Sweden; and 5Centre of Clinical Research, County of Ga¨vleborg, Sweden
Abstract Purpose: Despite a uniform regional breast cancer care program, breast cancer survival differs within regions. We therefore examined breast cancer survival in relation to differences in diagnostic activity, tumor characteristics, and treatment in seven Swedish counties within a single health care region. Methods: We conducted a population-based observational study using a clinical breast cancer register in one Swedish health care region. Eligible women (n = 7,656) ages 40 to 69 years diagnosed with primary breast cancer between 1992 and 2002 were followed up until 2003. The 7-year relative survival ratio was used to estimate breast cancer survival. Excess mortality was modeled using Poisson regression to study differences in survival between counties. Results: The 7-year relative survival for breast cancer patients was significantly lower (up to 7% in absolute risk difference) in one county (county A) compared with the others. This
difference existed only among women diagnosed before 1998, ages 50 to 59 years, and was strongest among stage II breast cancer patients. Adjustment for amount of diagnostic activity eliminated the survival differences among the counties. The amount of diagnostic activity was also lower in county A during the same time period. After county A, during 1997-1998, began to adhere strictly to the regional breast cancer care program, neither any survival differences nor diagnostic activity differences were observed. Interpretations: Markers of diagnostic activity explained survival differences within our region, and the underlying mechanisms may be several. Low diagnostic activity may entail later diagnosis or inadequate characterization of the tumor and thereby missed treatment opportunities. Strengthening of multidisciplinary management of breast cancer can improve survival. (Cancer Epidemiol Biomarkers Prev 2005;14(12):2914 – 8)
Introduction One of the major goals of a health care program is to ensure high quality and equal care among all residents. It is therefore disturbing that breast cancer survival differs among regions with similar breast cancer etiology and overall health care organization. Within regions, treatment by clinicians with specialist training, a longer practice, or a greater case load and treatment at larger hospitals or units with a larger annual case load consistently improves quality of care for breast cancer (1). Such improvements in quality of care (as measured by, e.g., compliance to guidelines) may affect breast cancer survival (2-4). Although promoting clinical guidelines may change breast cancer management (1), whether such management changes improve survival has not been adequately studied. Our study investigated breast cancer survival differences across seven counties contained within a single Swedish region with homogenous health care following the same clinical guidelines. For one county within the region, we hypothesized
Received 5/3/05; revised 9/12/05; accepted 9/26/05. Grant support: Swedish Cancer Society. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Note: The work was done at the Regional Oncologic Centre, University Hospital, SE-751 85 Uppsala, Sweden. Conflict of interest: No one of the authors have any financial or personal relationships with other people or organizations that could inappropriately influence this study. All the authors have had full access to all the data in the study. Requests for reprints: Sonja Eaker, Department of Surgery, University Hospital of Uppsala, SE-751 85 Uppsala, Sweden. Phone: 46-18-15-1920; Fax: 46-18-71-1445. E-mail:
[email protected] Copyright D 2005 American Association for Cancer Research. doi:10.1158/1055-9965.EPI-05-0317
that its lower survival rates resulted from its later adoption of regional treatment guidelines and later establishment of a multidisciplinary team coordinating management for breast cancer patients.
Materials and Methods Setting. Sweden consists of 21 counties, which are grouped into sex health care regions. Within each region, the county councils should collaborate with respect to highly specialized health care. In this study, we used information from a population-based breast cancer register that captures information on all breast cancers diagnosed in the Uppsala/ ¨ rebro health care region. This region consists of seven O Swedish counties and had a female population of 743,000 residents ages z20 years in the year 2002. The register began in 1992 when formal, written clinical guidelines were issued to ensure that all women with breast cancer in the region had the same opportunity for high quality care; however, each county organizes breast cancer management itself. The register includes 97% of all breast cancer patients in the region based on matches with mandatory reports to the Swedish cancer registry. The register ascertains information on vital status, age and date of diagnosis, detection mode, tumor stage, tumor characteristics, and primary surgical and oncological treatment. Subjects. The participants were all women with primary breast cancer reported to this register from January 1992 through December 2002 (12,163 women), with follow-up until December 2003. We excluded 105 (0.9%) women for whom we had
